The present invention relates to material handling method and apparatus, and more particularly to method and apparatus for stocking a builing under construction with wallboard or other panels.
Multi-story buildings are constructed of concrete or other load bearing materials used for the floors thereof, and interior divider walls are made of wallboard. The wallboard is manufactured in sheets or panels, having a uniform width of four feet, and a height of, typically, eight feet, ten feet, or twelve feet. The wallboard is relatively heavy, so that it is the usual practice for two men to lift only two sheets or panels of wallboard at a time. Wallboard installers receive the wallboard sheets, and attach them to studding, and since in a building of any substantial floor area, the amount of interior partition walls, and therefore amount of wallboard utilized, is quite large. The wallboard is manufactured, and shipped in large quantities to a building supply organization, which in turn sells the wallboard to the contractor charged with erecting the building. The wallboard must not only be delivered to the building site, but the building must be stocked with wallboard in sufficient quantities and with sufficient speed to enable the wallboard installers to proceed without delay in their tasks of installing the wallboard, by attaching the wallboard to the studding.
One widely used method of stocking buildings with wallboard is essentially manual, and labor-intensive. A truck loaded with one or more stacks of wallboard is driven to the building site, and is then unloaded, by a crew handling only two panels at a time. The two panels are removed from the truck, and are then put onto a cart. The cart, when loaded, is placed on a hoist, which is a temporary elevator, and then lifted to the desired floor. The cart is then removed from the hoist, and the wallboard is then removed from the cart, two boards or pieces at a time.
Another manual method which has been used is the lifting of a load from the delivery truck by lift forks suspended by a crane. The load is then lifted by the crane to the desired floor, where the lift fork is unloaded, two wallboards at a time. The wallboards are either hand-carried to a desired location on the floor of the building under construction, or are then loaded, two at a time, onto a cart, which is then moved to the desired location, and unloaded two wallboard panels at a time.
Both of the above manual methods require a large amount of labor. For example, a crew of six men at the building site are able to stock a building with only about 750 pieces of wallboard per day. Further, in the method utilizing a crane to support a lift fork, great difficulty, and consumption of time, has been encountered due to the inability to line the tines of the lifting fork with the openings or passages provided underneath the stack of wallboards. This difficulty has impeded the adoption of the method utilizing a crane.
Land, U.S. Pat. No. 3,876,099 discloses Apparatus for Delivery of Material to Floors of a Building Under Construction. This patent discloses a pallet with lift eyes, the pallet being equipped with rollers in order that a large, heavy object may be pushed on and pulled off of the pallet, and the pallet is also provided with guide rails in order that a box having wheels on its bottom may be rolled on and off of the pallet with the wheels engaging the guide rail. In using this apparatus for a large, heavy object, it is placed on the pallet by being rolled thereon; the pallet thus loaded is lifted to the desired floor, and the object is removed from the pallet by being rolled off. Alternatively, the box provided with wheels may be loaded with various materials, the loaded box then pushed onto the pallet, with the wheels engaging the guide rails, the loaded pallet then lifted, and then the box rolled off the pallet. The lift rings of the pallet are positioned so as to block lateral movement of the tines of a fork, so that a load cannot be placed on the pallet by a fork lift truck, thereby effecting a relatively slow loading of the pallet. Further, a transporter vehicle capable of receiving loads from the pallet is not provided, and the pallet itself, while having rollers, does not have any rollers which are powered, for ready and quick discharge of the load from the pallet.
Montgomery, in U.S. Pat. No. 3,861,546, discloses Apparatus for Lifting Wallboard Into Multi-Story Buildings. There are disclosed a generally L-shaped lifting apparatus, having lifting eyes for attachment of a sling. The lifting apparatus also is provided with guide rails, which receive the wheels of a generally L-shaped load carrying device. The carrying device has rollers provided on one surface of an arm of the L-shaped device, the underside of that arm being in the form of a locker; the bottom of the other arm of the L-shaped load carrying device is provided with wheels for engaging tracks on the L-shaped lifting apparatus. The lifting apparatus is also provided with a detachable leg. In use, the lifting apparatus is lowered, and a leg is attached in order to make it rotate about its longitudinal axis, with the load carrying device locked in place on it. Further rotation of the assembly causes the arm of the load carrying device having the rollers to be horizontal, and a fork lift truck is then used to place a stack of wallboard panels on the rollers. The panels are horizontal, and are strapped in position, after which the lifting apparatus with the loaded load carrying device is lifted by a sling, the entire apparatus rotating so that the panels of wallboard are vertical. After being raised to the desired floor, the load carrying device, loaded with wallboard panels in vertical position, is wheeled off of the lifting apparatus, and onto the deck or floor of the building under construction. The loaded load carrying device is then wheeled to a desired location, where it is unloaded by being turned onto its rocker surface of the one arm, after which the load of wallboard is discharged onto the floor or deck. This method and apparatus require careful positioning of the load carrying device onto the lifting apparatus, requires the attachment of a detachable leg to the lifting apparatus, and further requires the rotation of a heavily loaded load carrying device from a position in which the wallboard panels are vertical to a position in which they are horizontal, or beyond. These requirements, therefore, make this apparatus one which is relatively cumbersome to use, and also involves some danger in the handling of the stack of wallboard when it is being discharged from the load carrying device.
Pallets have long been used for supporting and lifting loads. Land U.S. Pat. No. 3,876,099 discloses a pallet having a frame, spaced sets of rollers, and lifting eyes positioned in line with the passages between the sets of rollers. Golrick U.S. Pat. No. 2,509,682 discloses a pallet with a surface made up of spaced apart bars, the passages between the bars being upwardly opening to receive the tines of a fork lift, the sides of these passages being unobstructed for lateral entry or withdrawal of the tines. Shaw U.S. Pat. No. 3,370,727 and Bryan U.S. Pat. No. 4,077,532 disclose that it is old to provide a supporting structure comprising a plurality of rollers and a powered wheel for advancing a box or the like carried by the support rollers. These known disclosures, however, do not provide a pallet suitable for use where a load of wallboard is to be placed thereon by a fork lift, the fork withdrawn in a direction parallel to the ends of the pallet, and then a load delivered from the pallet by a driven roller or the like energized by a self-contained power supply system.